Meter test block



July 21, 1936. E, G J HAN N 2,048,007

METER TEST BLOCK Filed March 6, 1934 faten ted July 21, 1936 was;

' ilviE'rca TEST 314001;

I Ernest G. J ohans son, Watertown, Mass., assignor toThe ,IjalmerElectric & Manufacturing Co., Waltham,-Mas s., incorporation ofMassachusetts ApplicatiomMarch 6, 1934, Serial No. 714,297

This invention relates to a meter test-block and means for mounting theblock in a meter terminal housing. 7 T i For various reasons there is a'present day demand for meter terminal housings occupying the smallestpossible space. Definite limitations are placed upon the minimumdimensions-of such a housing by the underwriters"requirements. The rulesrequire that there shall be between currentcarrying conductors ofdifferent polaritya prescribed minimum distance through the air and aprescribed minimum surface-distance on the insuslating member carryingthe conductors. Itis an object of the invention to .provide ameterterminal housing containing a test-block, the housing being of thesmallest possible dimensions consistent with the underwritersrequirements; and the test-block being of simple and convenientstructure capable of rapid and economical manufacture. It is a furtherobject ofthe invention to provide the test-block withnovel bridgingcon:- ductors which normallyconnect pairs of terminals on the block andwhich may be operated tobreak these connections, the arrangement andmaterials being such that, in case any 'considerable current is flowingthrough a bridging conductor atthe time of such a break;'the'resultan-tarc willbe immediately quenched. For a morecomplete understandingof-the-invention, reference may be'had to the description of anembodiment which follows and to an'illustration thereof on thedrawing,-=of which Figure l is a front elevation of a meter terminalhousing and test-block embodying the invention. Figure 2 is a section onthe. line 2-2 of Figure 1. Figure 3 is a section on the line3'3 ofFigure 1. Figure 4 is a perspective view, of thebarrier member forming apart of the test-block shown in Figure l. V

Figure 5 is a perspective view of a temporary connecter or jumper whichmay be used'on'the test-block when testing the meter. 1 a

Figure 6 is a perspective view of another barrier member forming a partof the test-block.

Figure 1 illustrates in elevation a meter terminal housing In, which maybe constructed, as usual, of sheet iron suitably stamped and shaped.This box or housing is preferably provided with a cover llhingedthereto. The boxwall 'm'ay be provided with an opening to receiveapipe or conduit l2 through which the line and load lead-wires may enterthe box; A portion of a meter is indicated at l5; Within the box I 0 atest-block is mounted. The test-block, as shown, may comprise a base l6consisting of a rectangular slabof insulating material such asvulcanized fiber. This Jmaterial is not only capable of being punched,drilled and tapped easily and accurately, but also 'has the property ofgiving off arcquenching gases when strongly heated. Advantage may betaken of the latter characteristic as -is hereinafter explained. Asindicated in Figure 3, the test-block may conveniently be mounted in thehousing I!) by means of a pair of brackets I! mounted on a side wall ofthe box to form an elongated channel adapted to receive one end of theslab iii. A sheet of insulation 18 is preferably secured to the sameside wall of the box, this sheet being provided with an elongated slotalined with the channel between the brackets I! so that the slab l6passes through the slot in the sheet l8 to engage the channel betweenthe brackets H. The opposite end of the slab I6 is fastened as by a bolt20 to a bracket 2i mounted on th adjacent wall of the box. Thus thetest-block can be easily and quickly mounted in place in the box orremoved therefrom. As hereinafter described, the test-block includesconductors adapted to connect with the wires leading to the line and theload. -A connecter 26 may be provided for neutral or ground wires, thisconnecter being secured at a convenient point to the rear wall of thebox In. In making the test-block shown on the draw- :ing, suitable holesmay be formed by punching, drilling, or otherwise, in the slab IE toreceive belts or equivalent fastening elements. These holes may-beformed rapidly and economically *by rapid process tools. In order toprovide for the proper spacing between current-carrying parts ofdifferent polarity, I provide barrier ele- =ments which are suitablylocated between such :parts; :According to the invention, such barrierelements are pre-formed and are assembled with the slab'lfi after theholes are formed therein but before the conductors are mounted thereon.Suitable barrier elements are illustrated in Figures 4 and 6, Figure 4showing a transverse barrier. 30 and Figure 6 showing a longitudinalbar- -rier 3| Each transverse barrier 30 consists of a sheet or slab ofinsulating material having an elongated slot32 formed therein, this slotbeing substantially the same size and shape as the 'cross section oftheslab l6 so that the slab may be inserted through the slot 32 for adriving fit. *Eachbarriermember 301s also provided with an- ;.other-slot33 at right angles to the slot 32, the lslot 33 having a width equal tothe thickness, of the longitudinal barrier 3|. This barrier is --notchedas at 34 soas to form mortised joints iwith=the barriers 30 when thebarrier 3| is forced 55 through the slots 33. in assembling the base andbarriers, the barrier 3| is forced through the slots 33 of the barriers30 and is then moved forwardly so that the bottom of the-notches 34 seatagainst the ends of the slots 33. A slab I6 is then forced through theslots 32 of the barriers 30, the parts fitting tightly in the slotssothat the assembled structure is rigid. The -"barriers are adjusted-topositions relative "to the holes in the base I 6, as indicated in Figure1..

these conductors also has a portion 46 ofiset forwardly'from the face ofthe slab l6. Geri-e sponding to the lower conductors, a set of upperconductors 50, 5|, 52 and 53 is provided, the -dimer conductors beingseparated from the lower conductors by the barrier 3| .As shown inFigure 2, each upper conductor is preferably U shaped and extends aroundthe upper edge of the slab [6. One arm 55 of each upper conductor bearsagainst the front face of the slab l-6., the other arm'iifi. bearingagainst the rear face of the slab The rear arm756 has an extension51pmjectingbelow the end of the front arm 55,-;

l The lower conductors may be secured to the base l6 by any suitablemeans. Asshown, each lower conductor is provided with a bolt pass- ,ing.from rear. to front through the slab it and 'throughthe portion of theconductor winch is against the front face of the slab. This bolt may actas .a binding post as well as serving to secure the conductor to theslab. Loosely mounted on theigbolt 60, I may employ a connecting 61, or.-this. lug being longitudinally split as at 62 for the greater, part.of itslength. The iug Si 'is also provided with a screw thre'adedubore63 at right angles to the bolt 60. The lug BI is preferably .made. of ametal which is sufiiciently harder than the copper commonly employed inelectric v'zires to be able to cut a screw thread on a wire which is ofsuitable size corresponding to the bore 63.

Thus, when .it is desired to connect a wire to one of .theloiwerconductors'eof the test block, a lug .61, screwed onto the end 50f theputting ascrew thread thereon. The lug then in position on the bolt .60.and a nut 65 is then 'screwed onto the bolt 6.0,.this' nut pressingtogether the jaws of the lug formed by theslot fl 'so that the threadedportion of the wiremhfch --is between the jaws inthe bore 63 is firmlyclamped therein. The nut 65*also-servesto clamp the lower conductorfirmly in place against .the

front face of the. base 15-.

V The arms 55-and 56 of each upper conductor are provided withholes inline with a correspondingholethrough the base 16.1 hole ".p'ref- --erably 'of a suitable size to receivefreely amend portion '66 of a wireleading to the meteiz. In prderto make a connection -betweeii the wireand the upper conductor, a, nut of sufficiently metal-is screwed ontothe end portion '55 as to cut a screw thread thereon. thread- 1-reuportion is then thrust through the alirxed holesin the arms '55 and56 and the base 136-. and

a' second' nut Hv is screwed :onto :tnererwamiy tion b'etwee'nthe upperconductor and the slab IE, but also provides an excellent electricalconnection between the upper conductor and the end portion 66' of thewire leading from the meter. 7 In order to hold the upper conductors inplace on the base l6 when the meter wires are not connected thereto,suitable screws 12 maybe provided, the base being tapped to receivethese screws." T

Betweeneach upper'conductor and its corresponding lower conductor, Iprovide a bridging cenductor or switching element, which, as shown, inthe form of a bolt 15. This bolt passes loosely'through a. hole in theoffset portion 46 are lower atc et-or and through a hole in the lifaiinedtherewith. The rearward end of the 15 is normally inscrew-threaded connection with the extension 51 of thecorrespondingupperrohductor so that it electrically con-V n6? itscorresponding upper and lower conductor'syah'd also clamps the extension51Vagainst 20 the rear'face of the base 16. In testing meters, it iscustomary to provide jumpers or the like for temporarily lay-passing theload current around th meter 59 hat, the test may be co-nductedwithutr-interrupting the service toythe' consumer; when these jumpers orby-passing connectors havevbeen attached, the meter I5 is then disconnected by backing off the switching elements 15 until theirccnnectionwith the corresponding 6X? ens ns .51 is broken. Since at such times the3.0

bull; of theload current is carried by the bypassing conductorsthere islittle tendency to are when the. switching elements 15 break theirconheel/ions with :the upper conductors. However,

it may be necessary i-n'emer'gencies to break the connection between aswitching element 15 and its corresponding upper conductor when theseparts are-carrryingga heavyload current. Since the switching element.necessarily moves slowly in an axial direction by reason of 'the screwice voltage is broken with little or no arc. .It is evident, however.from Figure 2, thatif such arc occurs. it must occur in aconfined cavityformed by ,the holegthroughthe extension 51 ordinarily failed by.thelrearward endof the bolt 15. Furthermore, such am will occurat apoint immedi ately adjacent to vulcanized fiber which, as here inbefo'restatedrhas the) ropertyof. emitting arc quenching gases when stronglyheated. Thus an are formed at the forward face "of the extension 51,would strongly heat the adjacent vulcanized fiber-so that apufi orexplosion of arcq-uenching gas would thereupon be generated so as toblow out the arc. By means of the structure thus described, arcs becomeself-quenching.

ordinarily connected, line wires lead to the conductor'sfdfl and 4].,the load wires being connected to the conductors 43 and 42. As .test

blocks of this kind are adapted to carry large so currents, that is, ofthe order of 100 amperes, it is desirable toe'mploy jumpers having aconsid *erable, area-of crossesection to carry'the by-passing currentwhile the test isbeingmade.

To this end. -a byapassing conductor, such as isillustrat- 55:;

ed in:5,, maybe employed. This consists of a piece of heavy copperhaving a pair of matches 84 suitably spaced-to receive the bolts -50which-hold dow'nthe conductors 41 and, these conductors being ofsimilarpotential. In' 'order 3m between them and the nuts 55; Toffacilitate 7 4o thread-,analternating current of ordinaryservmanipulation bf the member Bil. aconyenient g;

handle 85 may be provided as shown. During a test, it is likewisedesirable to connect temporarily the conductor 40 with the conductor 43.T facilitate such connection, I may provide a branch conductor 86connected to the conductor 40 and secured to the base l6 by a bolt 81and nut 88. Suitably spaced from the conductor 86 is a second conductor90 secured to the base by a bolt 9! and a nut 92. Between the head ofthe bolt 9! and the rear face of the base I6 is clamped a copper bar 95,which, as shown in Figure 3, extends behind the base IE to the bolt 60which secures the conductor 43 to the base. The bar 95 thus serves as apermanent electrical connection between the conductor 90 and theconductor 43. In preparing for a test, a bridging conductor 85 may beclamped to the conductors 86 and 99, thus effectively connecting theconductors 38 and 53. When these conductors have been thus connected,and the conductors 4| and 42 have been connected, the four bolts 15 maybe backed off sufiiciently to break the connections between the lowerconductors and the upper conductors so that the meter I5 is entirelydisconnected from the line and load wires and is thus ready to beconnected to a known load for testing purposes.

I claim:

1. A meter test-block comprising a base consisting of a slab ofinsulating material, a plurality of transverse insulating barriers onsaid base, each said barrier consisting of a plate having a slottherethrough adapted to receive said base with a driving fit, andconductors mounted on said base for connection with line, load and meterleads, conductors of different polarities being separated by saidbarriers.

2. A meter test-block comprising a base consisting of a slab ofvulcanized fiber, a set of conductors having end portions against therear face of said base, a corresponding set of conductors on the frontface of said base having end portions spaced therefrom, switching meanscomprising a set 'of bolts projecting loosely through the end portionsof the conductors on the front face of the base and through said baseand in threaded engagement with the end portions of respectiveconductors against the rear face of the base, and means on each saidconductor for connecting a wire thereto.

3. A meter test-block comprising a base consisting of a slab ofvulcanized fiber, a conductor secured against the front face of saidslab, the lower end portion of said conductor having a flange engagingthe bottom edge of said slab, the upper end portion of said conductorbeing forwardly offset away from the face of said slab, a secondconductor mounted against the rear face of said slab and having aportion in line with the offset portion of the first conductor,switching means comprising a connecting bolt passing loosely throughsaid offset portion and said slab and in threaded engagement with saidsecond conductor, and means on each said conductor for connecting a wirethereto.

4. A meter test-block comprising a base consisting of a slab ofinsulating material, an upper conductor having a U shape fitting overthe top edge of said slab so that the arms of the U rest against thefront and rear faces of said slab, the arm against the rear face havingan extension lower than the end of the other arm, a meter lead passingthrough both said arms and the slab between them, a pair of nutsscrew-threaded on said meter lead and bearing respectively against themutually remote faces of said arms, a lower conductor mounted againstthe front face of said slab and having a forwardly ofiset portion, and abolt extending loosely through said offset portion and said slab and inthreaded engagement with the exterior on said upper conductor, said bolthaving a head bearing against said offset portion.

5. An electrical device comprising an insulating base, conductors on thefront and rear faces respectively of said base, an accessible switchingelement passing loosely through one said conductor and the base and inthreaded engagement with the other said conductor, said switchingelement having a head bearing on said one conductor to clamp saidconductors against the base.

6. In a meter test-block, an insulating base including a slab ofvulcanized fiber having apertures therethrough, a set of conductors onone side of said base, a set of corresponding conductors on the oppositeside of said base, and switching means extending through said aperturesand respective pairs of corresponding conductors to efiect threadedclamped relation between corresponding conductors, said switching meansbeing accessible and operable to break engagement between correspondingconductors within said apertures.

'7. In a meter test-block, a slab of vulcanized fiber, a conductoragainst the rear face of said slab, a second conductor having a portionforwardly offset from the front face of said slab, said conductors andslab having alined holes therethrough, and a switching element extendingthrough said alined holes so as to connect said conductors electrically,said switching element being movable forwardly to break contact with therear conductor in a cavity formed by said holes through the rearconductor and the slab.

8. In a meter test-block, a base consisting of a slab of vulcanizedfiber, a pair of separate conductors mounted on said block, a switchingelement extending through said slab and normally engaging one of saidconductors in front of said slab and the other said conductor behindsaid slab, said switching element being movable to break the connectionat a point in a confined area and immediately adjacent to a portion ofsaid slab, whereby any are which may occur at

